what are the reasons IRS was not used on the 05+ mustangs?

 

Cost of development and retooling

 

Smart engineers who knew us drag racers would have to go through the trouble of riping it all out. God bless those men.

 

Because the solid rear axle was improved to the point that IRS was only marginally better in daily use, and the cost of IRS could not be justified. Remember that the 2005 Grand American Cup Road Racing Championship belongs to a 2005 Mustang with an SRA; it's up to the task.

 

Because the bean counters told them last minute to engineer the solid and save money on the IRS....

And they did a phenominal job on the 3-link SRA
As brad mentions, it has proved itself and was done AWSOMELY in the short ammount of time they had to engineer it

 

And because us Old Farts wanted what we had back in the late 60`s and early 70`s , a solid Posi-Trac rear end! WOO-HOO!

 

Dumb engineers (or bean counters most likely) that didn't appreciate that 99.9% of Mustangs are actually driven on lumpy, bumpy twisty real world roads significantly longer than 1/4 mile in length. How were we cursed with such narrow-sighted men.

Argument/discussion basically cleaves down the line between the drag racers and penny pincher contingent, who love the cheap and simple SLA, vs the (real world) road racers and canyon carvers, who want/need something better than a truck axle when the handling demands actually gets challenging.

While the SLA lively axle is a bit less lively than the River Dance SN95 buggy axle, the main reason was penny pinching, not superior performance (outside the narrow confines of a creamy smooth drag strip). The SLA is quite good for the type -- live axle -- even if that risks dam*ing it with faint praise, and suffices well on rather smooth roads or where suspension compliance considerations can be thrown out the window (drag and most track road racing).

Maybe with the Camaro and Challenger coming out, presumably with IRS, Ford will be shamed into offering, at least as a option, 21st century suspension technology for those who challenge their Stang's by more than a 1/4 spurts on a straight, smooth road.

But perhaps given Ford's dire financial straight's (caused by product engineering penny pinching???), we should be lucky that the Stang isn't saddled with leaf springs and drum brakes, just like the old farts had back in the late '60s and early '70s.

 

OMG... HELL HATH FROZEN OVER...
RHUMB said something GOOD about the SLA...
It was small...but it was good
hahahahah

Oh...this diserves a new custom title

 

Now now...that wasn't very nice...
Just because you don't agree with his views, doesn't mean you have to slam him

Please refer to the forum rules

 

Always said it was pretty good ... for the type ... just don't think the type -- live axles -- is the best overall performance solution for a 21st century performance car outside the rather narrow and limited confines of a drag strip (or trailer towing too).

 

If it's good enough for the FR500C, it's good enough for me.

 

Just buggin ya rhumb

 

You are really in the wrong car crowd. You know that right?

 

Stick around a while Jake. You'll see that Rhumb doesn't have many nice things to say about a SRA.... but we love him anyways.

Personally... I think he's a Closet SRA Liker... he'll come out one day, and we'll all be proud.

 

SRA was chosen over an IRS because Ford is run by accountants and MBA graduates instead of engineers and 'car guys'.

This is also why Ford is being run into the ground...and will probably cease to exist or be acquired within the next 3 or 4 years.

 

But it clearly wasn't good enough for the Ford GT.

 

Awww now, despite all my haranguing, the SLA isn't a bad suspension per se, especially if you're pretty narrowly focused soley on off-the-line / drag racing performance. There, it IS the best design. It's just that it isn't necessarily the best design in terms of well balanced overall performance and vehicle dynamics over a wider range of real world roads and conditions.

While the price argument can most credibly be made for the Base and GT models, it gets rather thin and tenditious when it comes to the GT500, especially given that Coletti and Co. proved it could be done effectively and affordably in the '99-'04 Cobras, a chassis far less amenable to recieving an IRS than the S197.

The irony is that, even with the supposed cost cutting measure of reverting back to a live axle in the GT500, it still commands a significantly steeper premium over the GT model than did the Cobra despite otherwise being an almost identical level of upgrade in terms of content and engineering (the 5.4 being little more than a tall-block version of the 4.6 SC Cobra motor). Just where does all that extra money then go if there's a lot less there?

As for the being around the wrong crowd, since when did the Mustang's performance identity get constricted to little more than club-footed, big-motored drag queen? Indeed, as originally conceived and executed, the Mustang was very much an ANTI-muscle car, that aspect of its character being a much later outgrowth.

 

Yes they cheaply designed possibly the worst IRS system on any car, ever. Good for them.

1964 or really 66-67 when Ford called Shelby in to give the mustang more juevos to try and compete with vettes, camaros, firebirds, etc. There's also a reason they are called "pony cars".

see above. They clearly WANTED that image only a few years after they started the mustang.

 

You could always buy a C6 with leaf springs.

 

The original GT40s had IRS to begin with. let's get back to campairing apples to apples here.